#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
#include <libavutil/imgutils.h>
#include <SDL2/SDL.h>

//Output YUV420P data as a file 
#define OUTPUT_YUV420P 1

int simplest_ffmpeg_player_su_sdl2_m(void)
{
	//FFMPEG-------------------------
    char filepath[]="resource/nwn.mp4";
    int				i, videoindex;
	int 			ret, got_picture;
    AVFormatContext *pFormatCtx;
    AVCodec			*pCodec;
    AVCodecContext	*pCodecCtx;
    AVPacket *packet;
	AVFrame	*pFrame,*pFrameYUV;
	unsigned char *out_buffer;
	struct SwsContext *img_convert_ctx;

	//SDL---------------------------
	int screen_w=0,screen_h=0;
	SDL_Window *screen; 
	SDL_Renderer* sdlRenderer;
	SDL_Texture* sdlTexture;
	SDL_Rect sdlRect;

	int y_size;
	FILE *fp_yuv;

    av_register_all();           //注册所有组件
    avformat_network_init();    //初始化网络库 可以打开rtsp http协议的流媒体视频
    pFormatCtx = avformat_alloc_context();  //解封装上下文
    //打开输入视频文件
	if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=0){
		printf("Couldn't open input stream.\n");
		return -1;
	}
    //获取视频文件信息    
	if(avformat_find_stream_info(pFormatCtx,NULL)<0){
		printf("Couldn't find stream information.\n");
		return -1;
	}

	videoindex=-1;  //一般0是视频流
    //遍历流元素数
	for(i=0; i<pFormatCtx->nb_streams; i++) 
		if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
			videoindex=i;
			break;
		}
	if(videoindex==-1){
		printf("Didn't find a video stream.\n");
		return -1;
	}

    pCodecCtx=pFormatCtx->streams[videoindex]->codec;
    //查找解码器
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
	if(pCodec==NULL){
		printf("Codec not found.\n");
		return -1;
	}
    //打开解码器
	if(avcodec_open2(pCodecCtx, pCodec,NULL)<0){
		printf("Could not open codec.\n");
		return -1;
	}
	//alloc
	pFrame=av_frame_alloc();
	pFrameYUV=av_frame_alloc();
	out_buffer=(unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P,  pCodecCtx->width, pCodecCtx->height,1));
	av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize, out_buffer, 
		AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1);

	packet=(AVPacket *)av_malloc(sizeof(AVPacket));

	//Output Info-----------------------------
	printf("--------------- File Information ----------------\n");
	av_dump_format(pFormatCtx,0,filepath,0);
	printf("-------------------------------------------------\n");
	img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
		pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);

	#if OUTPUT_YUV420P 
		fp_yuv=fopen("output.yuv","wb+");  
	#endif  

	if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)){
		printf( "Could not initialize SDL - %s\n", SDL_GetError()); 
		return -1;
	}
	
	screen_w = pCodecCtx->width;
	screen_h = pCodecCtx->height;
	//SDL 2.0 Support for multiple windows
	screen = SDL_CreateWindow("Simplest ffmpeg player's Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 
		screen_w, screen_h,
		SDL_WINDOW_OPENGL);
	
	if(!screen) {  
		printf("SDL: could not create window - exiting:%s\n",SDL_GetError());  
		return -1;
	}

	sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
	//IYUV: Y + U + V  (3 planes)
	//YV12: Y + V + U  (3 planes)
	sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, 
		pCodecCtx->width, pCodecCtx->height);

	sdlRect.x = 0;
	sdlRect.y = 0;
	sdlRect.w = screen_w;
	sdlRect.h = screen_h;

	//SDL End------------
    while(av_read_frame(pFormatCtx, packet) >= 0)	//从输入文件读取一帧压缩数据
    {
		if(packet->stream_index==videoindex)
		{
			avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);	//解压一帧压缩数据
			if(ret < 0)
			{
                printf("Decode Error.\n");
                return -1;
			}
			if(got_picture)
			{
				sws_scale(img_convert_ctx, (const unsigned char *const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
					pFrameYUV->data, pFrameYUV->linesize);

#if OUTPUT_YUV420P
                y_size = pCodecCtx->width * pCodecCtx->height;
                fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv);     // Y
                fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv); // U
                fwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv); // V
#endif
                // SDL---------------------------
#if 0
				SDL_UpdateTexture( sdlTexture, NULL, pFrameYUV->data[0], pFrameYUV->linesize[0] );
#else
                SDL_UpdateYUVTexture(sdlTexture, &sdlRect,
                                     pFrameYUV->data[0], pFrameYUV->linesize[0],
                                     pFrameYUV->data[1], pFrameYUV->linesize[1],
                                     pFrameYUV->data[2], pFrameYUV->linesize[2]);
#endif
                SDL_RenderClear(sdlRenderer);
                SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
                SDL_RenderPresent(sdlRenderer);
                // SDL End-----------------------
                // Delay 40ms
                SDL_Delay(40);
			}
		}

		av_free_packet(packet);
	}
	// flush decoder
    // FIX: Flush Frames remained in Codec
    while (1)
    {
        ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
        if (ret < 0)
            break;
        if (!got_picture)
            break;
        sws_scale(img_convert_ctx, (const unsigned char *const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
                  pFrameYUV->data, pFrameYUV->linesize);
#if OUTPUT_YUV420P
        int y_size = pCodecCtx->width * pCodecCtx->height;
        fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv);     // Y
        fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv); // U
        fwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv); // V
#endif
        // SDL---------------------------
        SDL_UpdateTexture(sdlTexture, &sdlRect, pFrameYUV->data[0], pFrameYUV->linesize[0]);
        SDL_RenderClear(sdlRenderer);
        SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
        SDL_RenderPresent(sdlRenderer);
        // SDL End-----------------------
        // Delay 40ms
        SDL_Delay(40);
    }
    
    sws_freeContext(img_convert_ctx);

#if OUTPUT_YUV420P
    fclose(fp_yuv);
#endif

	SDL_Quit();
 
	av_frame_free(&pFrameYUV);
	av_frame_free(&pFrame);
	avcodec_close(pCodecCtx);
	avformat_close_input(&pFormatCtx);
    return 0;
}
